It is frequently required to release adhesives from surfaces of objects without damaging the surface or the object. This is difficult to do, because the adhesive was designed to adhere very intimately to the surface or object. To remove the layer of adhesive immediately contiguous to the surface or object by mechanical means such as by scraping with a knife or spatula involves a considerable risk of scratching, and is rarely completely successful anyway. The use of abrasive compounds tends to dull or scratch the finish. It also is less than suitable.
Various solvents have been proposed for this purpose. However, known solvents and mixtures of solvents which are sufficiently effective to remove the adhesive by dissolving it generally are so strong that they can damage the surface, and so volatile that their effects are so short-lived that their use is troublesome.
Similarly, the removal of adhesive-backed labels from objects such as food packages is very difficult. In order to frustrate cheaters who would remove or alter the labels, they often are laid down in several separate adjacent segments. Attempts to remove such labels neatly by mechanical means are generally unsuccessful. The gum and the paper layers merely roll up or spread out, while still clinging to the surface. They make a mess.
There are solvents such as acetone, lighter fluid, or nail polish remover, which can be used to soften the adhesive under labels so the label can be scraped or peeled from a surface. Many of them are very flammable, and this is objectionable for many uses.
In addition, strong or active solvents can have an adverse effect on printing ink on labels or wrappings. They can and frequently do smear the printing, and can render a package unsuitable for sale.
Another problem with the use of strong or active solvents is that they must be left in contact with the adhesive or the label for a substantial period of time in order suitably to soften or dissolve the adhesive. They evaporate rapidly and do not provide sustained effects for extended periods of time. This requires the user to act quickly, or to repeat the process.
In times of rapidly rising food prices, labels on cans, boxes, foil and cellophane containers must frequently be removed in order that a new label with a new price can be applied. Because labor is costly, this work must be done quickly and efficiently, and the surface which remains should not require further treatment in order to accept a new label.
It is an object of this invention to provide compositions which act rapidly to release adhesives from surfaces so they and whatever they back, such as a label, can easily and quickly be removed from a surface or object without damage to the surface or deterioration of printed material.
It is yet another object of the invention to provide a composition which is quick-acting on labels, so that very soon after application to a label, the label is penetrated, the adhesive softened, and the label with the adhesive can be lifted cleanly with a blade, leaving behind a surface which does not require wiping or further treatment to be clean enough for sale, and for the reception of another gummed label. It is useful to remember that adhesives for labels are applied under optimal conditions, and are selected and applied so as to be quite adherent to the label itself. Therefore softening of the adhesive will preferentially release it from the surface, and it will accompany the label, when a composition according to this invention is used.
In accordance with this invention, a liquid composition is made up with a plurality of ingredients which exert mutually synergistic effects on adhesives and adhesive-backed labels. The ingredients include a first solvent, often having a high inherent volatility, that is selected for its property of being a good solvent for adhesives, and a carrier. The carrier is selected for a lower inherent volatility, so that the flammability of the total mixture is significantly reduced, for its "staying" power to remain without evaporation for a considerable time, and for its ability to dissolve the adhesive, or to hold in solution or suspension that which has been softened or dissolved by the first solvent. Advantageously, a second solvent can also be used. Preferably the first solvent is an aromatic, and the second solvent is a halogenated hydrocarbon solvent.
According to optional features of the invention, other components can variously be added to mask odors, to clean the surface, and to emulsify the composition if water is used as the carrier.